Overclocking. A rather large part of our lives. You might have noticed a small clue cunningly hidden within the title of the site. Trust us, it wasn't chosen because it sounds great, but because there are few things we like more than squeezing some extra 'free' performance out of something.

However, we know only too well that overclocking sits in a bit of a catch 22 situation. The people most needing to gain free performance are also the ones who can least afford the possibility of a processor dying on them. Times are hard for everybody, but many of us enjoy tinkering without necessarily having the funds to learn on our own hardware.

Our forums are the friendliest around, full of people who understand that we all have to start somewhere, but the culture of sneering is so ubiquitous on the vast interweb that we can appreciate some people don't want to reveal the secret that they don't know how to overclock their processor.

That's why we're here today. Whereas once overclocking was a dark art, with the latest, robust, Intel chipsets overclocking is extremely simple. We're not going to fill your brains with enough information to take you from a stock CPU through to the heights of a HiCookie overclock. So many guides flood you with information which is useful, but can be off-putting when you just want to get down to improving your system with the minimum of fuss. You want results, and you want them without having to wade through a tome worthy of a Tolstoy.

There are two important things we have to get out of the way. One : Disclaimer - Overclock3D cannot be held responsibility for any damages incurred when following the contents of this guide, you do so at your own risk. Two : Whilst we've cut out all the blather and pared this guide down to the essentials, it means that all the information is important, and page 7 especially so. For our part we'll teach you how to take your CPU beyond its stock specifications, if you agree to read it all.

What You'll Need

Before you begin you'll need an Intel CPU on a LGA1155 socket. You'll also require a copy of either wPrime or OCCT for stress testing (we're using OCCT), and a copy of CPUz. You can do without CPUz, but it's the default weapon of choice everywhere so you might as well grab it now. You might also want a seat, and a beverage of your choice, as well as about an hour.

When you load up OCCT, click the cog (third icon down) to access the settings screen as seen on this image. This is how it appears at defaults. For safety we highly recommend changing the core temperature limits, where it has all the 85s, to 80s. If you're really nervous you could drop it below that as an extra safeguard. With a good cooler (an absolute must) you're extremely unlikely to see these temperatures. Think of it more as a buffer in case your CPU cooler isn't as good as you think.

Ready to go?

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Setup

Many different motherboards are available, and one of the biggest differences is usually how well they overclock. With the rigid nature of the modern Intel chipsets a lot of the BIOS' are similar, and so whilst there will be cosmetic differences, we're limiting ourselves to the basics today, which should be available on whichever motherboard you happen to own. We're using the Gigabyte Z77-UD5H, which is a midrange number and more than up to the task we've set it today. It's probably the most common motherboard around too, so

Similarly, most CPUs available should be capable of the numbers we're reaching today, so whilst we're using our Core i7-3770K it isn't a vital part of the equation. We're utilising a Thermalright Silver Arrow as always. As heat is pretty much the limiting factor in overclocking, CPU coolers are certainly something we wouldn't recommend scrimping on and if you're using the one that comes in a retail CPU box, then return once you've brought one better suited to the task.

One of the useful elements of the UD5H is the on-board CMOS clear, reset and power buttons. As you're guaranteed to lock the computer up at one point during the overclocking process, then having the buttons readily to hand is, if you'll forgive the term, handy. Not vital though, so don't panic if you're without them.

BIOS

Thankfully for those new to this, which should be all of you, despite the array of options available in the BIOS we're only going to be adjusting a few of them. We know you're all champing at the bit to get on, but we have a few housekeeping issues to cover before starting the overclock. Consider this the equivalent of learning which end of the horse has the teeth before you go sticking sugar lumps in it.

The two main places we'll be visiting today are the Frequency Settings and the Voltage Settings.

This is how things look on an entirely fresh installation of CPU and motherboard. Handy to have a starting point. Should it all go wrong, which it wont, you can always just reload the optimised defaults. Also note that we're running our memory at 1600MHz. Partially because we know that not everyone has fast memory to hand, and also because if you run at a very standard memory speed you can be assured that your overclock isn't failing due to the stress placed upon the memory controller. It's yet another way we're trying to save you tearing your hair out.

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vDroop

Yes we know we promised to stick to the important stuff, and this is very much important. Without vDroop adjustment you'll be banging your head against the wall, which isn't conducive to an enjoyable experience. The basics of overclocking are to attain the maximum speed for the smallest voltage. So there always reaches a point at which you have a system running at a certain speed at a certain voltage, which is just enough to keep it running but with less voltage the overclock will fail and the system freeze or reboot.

vDroop is when, under loading, the amount of voltage being delivered is less than required. Thankfully we can demonstrate vDroop perfectly. We have manually set the CPU voltage to 1.13 (we'll explain why on the next page) and then started OCCT, which will induce the voltage drop and show you clearly why vDroop is a very bad thing, especially for stable overclocks, and your forehead.

The stages of the loadline calibration are usually named differently on different brands so you'll have to adapt, but the end result is that you want as much loadline calibration as is available to you. If you're without the manual, or the manual is unclear, then by doing what we have done today which is set your voltage, adjust the loadline, run OCCT and view the Voltage-CPU-VCore image which help you narrow it down to the setting you require.

Of course you can always ask in our friendly forums too, but we recommend getting used to adjusting a BIOS option, saving, booting, running OCCT and adjusting. Largely because you'll be doing a lot of it on the next page, but also because this is the shortest sane overclocking guide around and we've already cut all the corners for you.

Default

On our Gigabyte motherboard it's labelled Vcore loadline calibration. You'll usually find vDroop under loadline calibration if it isn't labelled vDroop already. Set to 'auto' you actually end up with no loadline calibration at all. With everything set as defaults except for the CPU Vcore set to 1.13v as noted above.

As you can see from the graph on the right, the moment the system comes under loading the CPU Vcore drops from 1.13v to 1.05v. For a standard CPU it's not the end of the world, but as we're not here for standard CPUs and by the end we'll be adding less than the 0.08v to attain our stable overclock, you can see how this drop would be fatal.

Low

There are many options for controlling the vDroop with the UD5H, but as we'll soon see you only need one. Indeed we've often commented that loadline calibration should be on all the times by default and if there is a BIOS option it should only be on or off, rather than the multi-stage affair we normally encounter. With the loadline calibration set to 'Low' we drop from 1.13 to 1.08, which is better than before but not perfect.

High

High is getting much better, but there is still a hefty dropoff from 1.13v to 1.1v.

Extreme

Finally we get to Extreme, which really is misnamed. Instead of Extreme it should be labelled 'How it should be done'. As you can see as soon as the system comes under loading the voltage remains rock solid. Exactly what we need for a stable overclock.

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Time to Overclock

Set your voltages!!

Hopefully having seen the hideous vDroop you get on 'auto' you'll have learnt the single most valuable lesson about overclocking and motherboards in general. However, it's such a vital thing we're going to say it again, in bold, and using a nice eye-catching colour. Do not trust 'auto'. It isn't a "be as gentle as you can be please Mr Motherboard" setting. It's usually the ultimate short-cut taker. The kind of person who'd just skip all this, set their voltage to 1.4 and see how far they could go.

So, into your voltage control and manually change the voltages from auto to what they should be. Like so. Now we have a sense of control. Control is key. If you're still disbelieving in the evils of auto then we've got a page especially for you coming up.

Out the box

As always it's nice to get a feel for how things are prior to tinkering. Our i7-3770K defaults to 3.5GHz with Intel Turbo enabling it to run at 3.9GHz. We'll be turning the Turbo off in a moment, another option that helps wrest control to us. Control is obviously important because we don't want the system doing anything behind the scenes that we haven't planned for. By limiting its chances at fiddling about it makes it much easier to debug our overclock.

On the right is the OCCT error screen, something you'll get used to seeing. This doesn't require anything changing anywhere, and will stop on errors by default. Hopefully you've also set your temperature threshold back on page one, so you can be safe in the knowledge that you wont kill anything during testing.

The internet is awash with people telling you how long to run OCCT/wPrime, whether to run blended or Linpack or whatever. Realistically you can run it for as long as you want. However, we have a few guidelines and we know you're desperate to get on with it.

Firstly you shouldn't run it for any less than an hour. You need the heat generated to soak through your case and reach an equilibrium. Your CPU will warm up in the first minute or so, but until that heat radiates through the case and warms the air up, which will limit the chilling capacity of your cooler, you wont really know how warm your CPU will get. You wouldn't play a game for less than an hour, and you wouldn't want your system to keel over just as you were winning. Secondly, the further from stock that you go, the longer you'll need to run it to ensure stability. However this has the slight side benefit that initial creeps up the overclocking scale are less likely to make your system fall over, so you can get away with shorter times to begin with. As always though, if you can be patient you will be rewarded and certainly once you reach the level you feel you want to run your system at forever then you should definitely run OCCT for a few hours to be certain.

It's worth noting that the voltages and ratios on your system might be different, depending upon your system specifications. Thankfully though the Intel range is so similar and bulletproof that the general principles (adjust a small amount each time and test a lot) apply whatever your setup.

Phew. Preamble out the way, let's crack on.

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Initial 4GHz

As we know from the above that our CPU can handle 3.9GHz perfectly well (as seen from the Turbo mode) then 4GHz isn't much of a stretch. However, it's a great number psychologically, and because it's not something you get as default but have to do manually, then you have performed your first overclock.

To reach these dizzying heights we've simply disabled the Turbo Boost, so that the chip runs either at the low-power state or our overclock, and adjusted the CPU Clock ratio to 40. Yes we know that sounds too easy. It isn't.

We aren't surreptitiously tweaking things behind the scenes, or giving you a "to play the flute simply blow in one end and move your fingers up and down" reduction of a complicated act to an 'as you know' simple statement.

Just turn off Turbo, set to 40. Tada. Or if you're on an alternate CPU to our model, set your CPU Ratio to one higher than the default Turbo speed was. Run OCCT for an hour until you're sure it's all gone well, and then move on to the next step.

4.4GHz and Voltage Increase

For the purposes of brevity we've skipped a couple of steps in our images. What we did was, as our 4GHz overclock proved stable, returned to the BIOS and solely increased the CPU Ratio (multiplier) from 40 to 41. Then saved the BIOS, rebooted to Windows, loaded OCCT and tested for an hour to ensure stability. We continued this process until, at a ratio of 44, the system failed. Returning to the BIOS, we entered the voltage section and solely changed the CPU vCore from 1.13 to 1.18. 0.05v isn't much, but enough to pass OCCT testing.

You might need more, or less. That's the difficulty with overclocking. You should never follow a guide in a "put this number here" way, because all of our components are different. Some of you might have needed more volts to reach a multiplier of 41, and some of you might have reached our 44 ratio still on the default CPU voltage.

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Going Further

4.5GHz

When we first postulated an article such as this, we chose to stay within the 4.4GHz boundary. It's achievable on almost any processor at all, and doesn't require extraordinary voltage or cooling to attain. Having got 4.4GHz from only a 0.05v bump in voltage we were tempted to see how much more could be had without remotely out-reaching a level of vCore that first timers would be comfortable using. It's also important for us to not do what a lot of guides do and start with a 100MHz overclock and, within a couple of CPUz's, be a 6GHz on LN2.

Retaining the exact settings we've used so far (Turbo off, Loadline calibration to Extreme, manual voltages, CPU @ 1.18v) we bumped the CPU Clock Ratio up from the 44 we left it on to 45. Yet another reboot and off to make a coffee whilst OCCT does its thing, and things are looking rosy.

4.6 Final

46 Ratio giving a 4.6GHz CPU speed fell over at the forty minute mark in OCCT, but a final increase of the CPU vCore from 1.18v to 1.2v saw things fully stable, and that's where we'll leave our overclocking adventure. We think you'll agree that 0.07v increase, for a 1.1GHz overclock above stock, isn't bad going at all.

Now let us remind you of why "Auto" is evil, and should never be relied upon.

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The Perils of Auto Voltage

Remember how we've been brow-beating you about the importance of having control over your system, and how AUTO is just the worst setting for CPU vCore known to man? We took our 4.6GHz @ 1.20v stable overclock from the previous page and solely adjusted the vCore from 1.2v to AUTO.

Look at how unchanging our voltage was throughout the preceding pages. Now look at how it is when just sitting at idle. 0.984v, 1.164v and 1.294v. Just doing nothing.

The one on the right is the CPUz from the moment we hit the OCCT go button. 1.404v. Exactly the same setting everywhere as was flawless at a manual 1.2v. Auto somehow believes we need 1.4v to achieve the same thing. This is a) above Intel recommended specifications b) an absolute heat bomb.

See how the graph climbed to the sky the moment OCCT was engaged. So horrific was the amount of voltage it used, that we hit the 80°C threshold in 20 seconds. TWENTY SECONDS to break the 80°C limit. On an overclock that was otherwise utterly stable forever on the settings we slowly worked towards.

Hopefully that's enough to make you never touch AUTO voltage ever again. You, your wallet and your hardware will thank you for it.

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Undervolting

By looking at how far we could go on the initial default voltage (3.5GHz to 4.3GHz) it shows that there is a certain amount of voltage overhead built in by default. So if we have a lot of headroom it stands to reason that it must be possible to reduce our CPU voltage, and thus the power draw and running temperatures.

The process for running on fewer volts than is standard is exactly the same as we use for overclocking, but naturally in reverse. Starting from the 1.13v we gradually reduced until we eventually reached the lowest voltage at which the CPU was stable under Turbo loading, which ended up being a particularly low 0.94v. Stunning stuff.

Temperatures

Because voltage generates heat our CPU had identical temperatures from stock settings up to 4.3GHz, largely because it had identical vCore. The small bump to 4.4GHz hasn't had a major increase in voltage, nor temperatures, and even the 1.2v needed for our final overclock of 4.6GHz didn't increase the temperature particularly high.

All those temperatures were taken after an hour of OCCT. Except for the 4.6GHz @ Auto Volts, which lasted precisely 20 seconds before hitting the limit we'd set and stopping the test.

Our undervolting shows how much cooler you can make your system run. 17°C cooler than it is at stock. If that isn't worth the little effort it takes, we don't know what is.

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Final Thoughts

The trick is to always increase the minimum possible. We know it's tempting to say bugger it and just jump in steps, but you must resist the urge. You're reading this because you want to overclock in a wholly safe manner, and the safest manner is to go one step at a time. For voltage purposes one step can be considered 0.05v (1.13, 1.18, 1.23, 1.28 etc). It's vital to keep an eye on your temperatures, hence the long OCCT run, and we'd recommend staying below 1.30v on the CPU vCore. 1.35v is what Intel tell you to stay below, but get comfortable within the very safe 1.3v limit for now.

No, that isn't an excuse to go "oh cool, 1.3 volts it is then". You always want the minimum voltage possible. Not only for temperatures, but also for your CPU lifespan. Yes that is a real thing and we can tell you tales of CPUs we've had here at OC3D that, after running on a leading edge overclock for a while, simply refused to run a stable overclock again, even at far below speeds it once took in its stride.

Hopefully you've taken on board the following touchstones. Ensure your loadline calibration is set to whatever setting enables zero vDroop. Always increase the ratio until the system ceases to be stable, then increase the voltage manually by 0.05v until stable. Then repeat the process until your CPU cooler can take no more, or you reach the 1.3v CPU limit. We're certain that with some time spent getting familiar with the processes we've outlined today, not minding the lengthy wait whilst OCCT determines if it's stable, and assuming your temperatures remain tolerable, that you'll be comfortable overclocking your system forever more.

Let us know what you think in our forums, if you have any questions please ask them there thats what they are for!